A mobile communication network includes a Radio Access Network (RAN) and a Core Network. A 3G mobile communication core network includes a Circuit Switched (CS) domain and a Packet Switched (PS) domain. An LTE mobile communication core network includes only a PS domain.
A PS-only subscription refers to a service subscription type that provides a user equipment (UE) with all of subscribed services (e.g., packet bearer service, SMS) only through a PS domain.
However, a typical SMS service method has drawbacks in an LTE mobile communication network. For example, an additional procedure is required, a CS service should be used, or a UE may fail to receive a part of information required for providing a service.